In recent years, a valve timing controller enabling varying of opening/closing timings of an intake valve and an exhaust valve in accordance with an operational state of an internal combustion engine (may be referred to also as “engine” hereinafter) has been put into practical use. This valve timing controller has a function of varying the opening/closing timings of the intake and exhaust valves opened/closed in association with rotation of a driven-side rotary member by e.g. changing the relative rotational phase of the driven-side rotary member relative to rotation of the driving-side rotary member caused by an operation of the engine.
In general, the optimal opening/closing timings of intake and exhaust valves differ, depending on an operational state of the engine such as engine start-up, vehicle run, etc. Then, at the time of engine start-up for instance, by restraining the relative rotational phase of the driven-side rotary member relative to rotation of the driving-side rotary member to a predetermined phase between a most advanced phase and a most retarded phase, opening/closing timings of the intake and exhaust valves optimal for the engine start-up are realized and generation of hitting noise by pivotal displacement of a partitioning portion of a fluid pressure chamber formed by the driving-side rotary member and the driven-side rotary member is restricted at the same time. After the engine start-up, the relative rotational phase is maintained under the restrained state for the purpose of warm-up for instance, while the vehicle stays stopped. But, when the vehicle is caused to run, the restrained state will be released since there now arises a need to change the relative rotational phase.
In PTL 1, there is disclosed a valve timing controller having a plurality of rotational phase restricting mechanisms configured to allow relative rotation which causes a relative rotational phase between an outer rotor and an inner rotor to approach a locking phase, but restricts relative rotation which causes the relative rotational phase to depart from the locking phase. With this valve timing controller, the relative rotational phase is at the most retarded phase at the time of engine stop, but not locked to this phase. At the time of engine startup, the relative rotational phase is varied from the most retarded phase to the phase advancing side due to cranking of the crankshaft and is restrained to a locking phase which is a phase between the most retarded phase and the most advanced phase. Thereafter, the locking will be released when the relative rotational phase is to be changed.